The present invention relates to a pointer type instrument adopted for, for example, an instrument for a vehicle, and particularly to a pointer type instrument of a type in which a pointer is brightened by lighting of a light source.
Conventionally, a pointer type instrument is known in which a pointer fitted to a rotating shaft of a driving unit formed of, for example, a stepping motor type or movable magnet type motor and interlocking with the rotating shaft to be rotated above a display board, is constituted by a translucent indication member including a light introduction part at a back side of a rotation center region, and illumination light of a light source disposed behind the display board is made incident on the light introduction part of the indication member through a light passing part of the display board, whereby the indication member (pointer) emits light brightly.
In the pointer type instrument of this kind, since the rotation center region of the indication member is covered with a light shielding cover member in which its front and periphery presents a cap shape, a light leakage from this part can be suppressed. However, the back side of the rotation center region must be exposed to introduce the illumination light. Thus, there has been a case where the illumination light leaks into a surrounding area from a gap part as a clearance between the cover member and the display board, this leakage light is reflected by the display board to produce halation, and commodity quality is damaged.
From such circumstances, as disclosed in, for example, Japanese Utility Model Publication No. 20097/1994 and as shown in FIG. 11, a pointer type instrument is proposed in which an annular light shielding ring C is provided around a light passing part B made of a through hole of a display board A as a light introduction path of illumination light, and this light shielding ring C is lapped over a cover member D, whereby the illumination light leaking into the outside from a gap part E is suppressed. Incidentally, in the drawing, reference character F designates an indication member; G, a pedestal member (covering member) for fixing the indication member (pointer) F to a rotating shaft of a driving unit; H, a light guide body for guiding the illumination light to the indication member F, F1, a light introduction part of the indication member F; and G1, an exposure part for exposing the light introduction part F1 and enabling the passing of the illumination light.
However, as described above, the conventional structure is such that the light shielding ring C and the cover member D are lapped over each other while a predetermined interval is provided, and the light leakage is suppressed, and there is a defect that in the illumination light traveling toward the side of the indication member F, the illumination light reflected by the back surface of the pedestal member G is apt to leak out from the gap portion E through a space between the light shielding ring C and the cover member D, and in this point, there is room for improvement.
The present invention has been made in view of this point, and has a primary object to provide a pointer type instrument in which a light leakage to the side of a display board is reduced and illumination quality can be raised.
A pointer type instrument of the present invention comprises a pointer which includes an indication member made of a translucent resin material and brightened by illumination light introduced from a back side of a rotation center region, and a cover member covering its outer periphery except for the back side of the rotation center region and made of a light shielding resin material, and is driven to be rotated through a driving unit formed of, for example, a stepping motor; a display board which is disposed behind the pointer, is apart from the cover member with a gap part intervening, and includes a light passing part corresponding to the rotation center region; and a light source disposed behind the display board, for generating the illumination light, wherein a leakage light prevention part for suppressing a light leakage from the gap part is provided on the back side of the rotation center region except for an introduction part of the illumination light, whereby the illumination light traveling to the gap part can be reduced, the light leakage to the outside (side of the display board) is effectively suppressed by this, and illumination quality can be raised.
The leakage light prevention part may be directly formed on the back surface of the rotation center region of the indication member. In the case where a covering member covering the back side of the rotation center region and provided with a transmission part enabling the passing of the illumination light is fitted to the pointer, the leakage light prevention part can be formed on the back surface of the covering member which becomes the introduction side of the illumination light.
As the leakage light prevention part, for example, a plurality of protrusions for blocking out the illumination light traveling toward the side of the gap part or an inclined surface for reflecting the illumination light to the side of the rotation center can be provided, and further, a crimped surface for diffusing the illumination light may be provided, and an arbitrary structure can be selected as long as it can reduce the illumination light traveling toward the gap part.